A team of scientists, including air quality research scientists from Environment Canada, undertook measurements of properties of ambient atmospheric black carbon particles to determine real-world solar radiation absorption by atmospheric black carbon. This research was part of a comprehensive field study of atmospheric processes conducted over California and the eastern Pacific coastal region in 2010. The results are presented in a peer-reviewed paper published in the preeminent research journal Science on August 31, 2012.

This study is part of a series of research and field projects conducted by Environment Canada’s Air Quality Research Division research scientists, chemists and engineers on black carbon issues. Black carbon emissions, their associated environmental and health effects and contributions to climate change issues have become a priority for the federal government. On February 16, 2012, Minister Kent, along with international partners including the United States, launched a new global initiative, the Climate and Clean Air Coalition to Reduce Short-Lived Climate Pollutants that will serve to reduce emissions, including those of black carbon.

Black carbon is formed from the incomplete combustion of carbon-based fuels (e.g., fossil fuels and wood) and exists in the atmosphere as solid particles. In Canada, black carbon emissions come primarily from biomass burning and transportation. Black carbon (soot) particles absorb solar radiation. In the atmosphere, these particles are coated by water and other chemical components, which vary in the atmosphere and differ for individual black carbon particles. The assumption used in current climate models has been that, when coated, the black carbon particles have as high as two times the impact of uncoated particles on the absorption of solar radiation. Recent research using real-world measurements shows a smaller effect.

The science on climate impacts of black carbon is still in its infancy and net climate impacts are influenced by other aerosols in the real-world mix. Black carbon is always emitted as part of a mixture of pollutants (i.e., organic materials). Therefore, it is important to understand how the effect of black carbon on climate is influenced by the aerosol mixture. Climate-forcing effects of black carbon and other aerosols continue to be a major focus of scientific research.

Contact: Dr. Shao-Meng Li, (416) 739-4281, Shao-Meng.Li@ec.gc.ca, Air Quality Research Division